Lv 4 You will have to kill プリ, one time only quest.
Lv 5 to 8 You will have to kill 砕貝.
Lv 9 to 12 You will have to kill チビコラナ.
Lv 13 to 16? You will have to kill ぬすっともんきー
Lv 17? to 19+? You will have to kill 青ペンギン

NPC Quests

See フレンチメイド (rough location on map above). Lv 5 Req. You will need to use your drill (make sure it's equipped). Drilling in フィールド１ and フィールド３ should get you what you need, フィールド５ is better for drilling but be sure not to accidentally attack any monsters. You need to be level 5 to accept this quest but you can start drilling right away.

Quest 2:

See マーメイドマリン (rough location on map above). Lv 5 Req. Another drill quest, any field will do.